Identification of a Novel Haloarchaeal Species Halorubellus amylolyticus sp. nov., Isolated from Salt Crystals of Salted Seaweed Knots and Genomic Insights into Genus Halorubellus

An extremely halophilic archaeon named strain PRR65^T was isolated from a salt crystal of salted seaweed knots which were purchased from a supermarket in Wuhu, China. It exhibited an ability to hydrolyze starch. Strain PRR65^T is a coccus. Its growth range and optimum concentration for NaCl are 2.0–5.1 M and 3.4 M, respectively, and it requires magnesium ions (with an optimum concentration of 0.01 M). Homology search of the 16S rRNA gene sequence indicated that strain PRR65^T shows the highest sequence similarities with Halorubellus salinus GX3^T (96.97%). The basic growth conditions and many other physicochemical characteristics of strain PRR65^T are distinct from those of other species within its genus. The average nucleotide identity (ANI), average amino acid identity (AAI), and digital DNA-DNA hybridization (dDDH) values between strain PRR65^T and its close relatives were 88.97%, 86.47% and 39.2%, respectively. The DNA G + C content (mol%) for strain PRR65^T is 67.2%. Based on a polyphasic taxonomic approach integrating phenotypic characteristics, chemotaxonomic markers, and comprehensive phylogenetic and genomic analyses, strain PRR65^T represents a novel species within the genus Halorubellus. The name Halorubellus amylolyticus sp. nov. is proposed, with the specific epithet reflecting the organism’s notable amylolytic activity. The type strain is PRR65^T (= MCCC 4K00175 = KCTC 4323)